1. Field of the Invention
The invention relates to a continuous casting apparatus.
2. Description of the Prior Art
During a continuous casting operation, molten material is teemed into a cooled mold where the material is at least partially solidified to form a continuously cast strand. The mold, which is oscillated during continuous casting, is supported by a mold table driven by an oscillator.
In a continuous casting apparatus for the casting of wide products, e.g., slabs having a width greater than 60 inches, the mold table consists of two parts which are spaced from one another. For proper operation, the mold table parts must be oscillated synchronously.
One conventional system for oscillating the mold table parts employs two eccentrics. Each of the eccentrics acts on a push rod which, in turn, is coupled to one of the mold table parts. The push rods have adjustable lengths to permit leveling of the mold table parts. A gear mechanism is located between the eccentrics, and two shafts connect the gear mechanism to the respective eccentrics. The gear mechanism is driven by an electric motor.
This electromechanical oscillating system is associated with substantial difficulties arising from the fact that the two mold table parts must be oscillated in synchronism. To begin with, all elements of the drive system, including the eccentrics, couplings, bushings and keyways, must be machined with a high degree of precision. Furthermore, all elements of the drive system must be very accurately aligned. Aside from these difficulties, the cost of the system is high because the system is complex and two eccentrics are required.
Another conventional oscillating system employs two hydraulic cylinder-and-piston units which are coupled to respective ones of the mold table parts. The hydraulic units, which extend and retract to generate an oscillating motion, are supplied with hydraulic fluid from a common reservoir.
The need for synchronous movement of the mold table parts creates substantial problems for the hydraulic system also. The hydraulic units must not only be machined with a high degree of precision but must be equipped with electronic position feedback sensors and a very complex servo mechanism. Moreover, excellent tuning and continuous readjustments are required. Additionally, this system is expensive because considerable maintenance is necessary and two cylinder-and-piston units must be used.